'Banks would have to consider whether to carry on with investment banking or focus even more on asset management', Widmer-Schlumpf was quoted as saying in an interview with Schweiz am Sonntag. Banks 'must be organized in such a way that the state isn’t ultimately held liable'.

The focus on leverage is the latest effort by the government and financial watchdogs to prevent a repeat of taxpayer-funded rescues of systemically important banks. UBS was bailed out in 2008 after booking more than $57bn in writedowns and losses in the U.S. sub-prime lending crisis. Regulators say the leverage ratio, now 4.5%, provides a safeguard against risk-based valuation rules that allow banks to weight assets depending on how they judge their safety.

'We must consider whether the capital-adequacy base shouldn’t be strengthened further', Widmer-Schlumpf was quoted as saying by the newspaper. 'Currently 6% to 10% are being discussed' as a leverage ratio, she said, adding the present level is 'too low''.